/Engine/Source/Runtime/CoreUObject/Public/UObject/PackageResourceManager.h
DoesPackageExist that takes a PackageSegment
bool DoesPackageExist ( const [FPackagePath](API\Runtime\CoreUObject\Misc\FPackagePath) & PackagePath, EPackageSegment PackageSegment, [FPackagePath](API\Runtime\CoreUObject\Misc\FPackagePath) * OutUpdatedPath )